Hello there,
Thank you for your reply.
My approach has been the follwing:
Firstly i did some basic research in openCV, i learnt that images are converted to matrices with numbers ranging from 0 to 255. My assumption was that since I have a computer generated image i should have a background thats all the same number without any variotion.
When I inspected the code i found that there is a treshold that i can input to detect the color change. With my current understanding, and by inspecting the matrices I found that 255 is the color white. So if i put the cropping treshold at 254 i should be able to find the boundaries when color begins. Ive also tried 1,255 49,255 and 150,255 but no effect.
I’ve also learnt from the code that the image is being converted from RBG to RGB and then to BW. I know that when a color spectrum is made black and white there is no difference between red and white. Therefore i changed the arrow color to blue. Unfortunatley that did not work.
Currently im reserachting what morphology is because i think the problem lies here. But this has been unsuccesful 
As for your final question, I actually have no idea what that means, I would assume the whole rectangle that overlays the image instead of a bounding contour? It would be really helpful if i could get some more information on this.
Thank you again.